NEW YORK (AP)  Forty years ago, the world”s top two marathon runners were each handed an envelope with a check in it for $3,000  secret rewards for helping raise the profile of the very first five-borough New York City Marathon.

“It was an instant hit, a ”Wow!”” says George Hirsch, chairman of the board of the New York Road Runners club that on Sunday hosts the 2016 race.

What is now the world”s largest marathon began in 1970 when 126 men and one woman circled Central Park. Six years later, about 2,000 amateurs, including Hirsch, took the race to the streets of New York for the first time, touching all five boroughs.

Leading the pack were American marathon record-holder Bill Rodgers and Olympic gold medalist Frank Shorter, paid to push the 26.2-mile run into the global spotlight. Hirsch  then a prominent publisher  passed them the checks “under the table,” he remembers.

“We wanted to give the most important runners in the world an incentive to be here,” Hirsch says. “They made a big difference.”

Rodgers won the first of his four New York marathons.

The payments to hit the pavement certainly paid off.

This year, about 50,000 people from more than 120 countries  half of them women  have registered. The elite athletes will be competing for a prize purse totaling $803,000, with potential time bonuses. The men”s and women”s champions will each receive $100,000. And $25,000 goes to the fastest competitor in a wheelchair.

All eyes will be on the two Kenyans who won last year  Mary Keitany, also the 2014 champion, and Stanley Biwott.

Among Americans, Gwen Jorgensen, the triathlon gold medalist at the Rio Olympics in August, will be running her first marathon. Molly Huddle, who set a U.S. record while finishing sixth in the 10,000 meters in Rio, is making her first try at this longer distance.

The star-studded American field also includes Olympians Dathan Ritzenhein and Kim Conley, who is making her marathon debut.

Scattered amid the crowded, sweaty runners will be eight amateurs in their 60s and 70s  all trailblazers in New York in 1976.

Dick Traum was the first person to complete a marathon with a prosthetic leg, in 7 hours, 24 minutes. Asked to step off ahead of the thousands of others, he was the first person to start the five-borough marathon.

“I ran as if you broke your leg and had a cast, trying to get across the street quickly, hopping-style,” says Traum, who has a business Ph.D. and created his own computer app company to help companies maximize resources.

At 75, he”ll mount his handcycle Sunday at the start line near the Verrazano-Narrows Bridge in the borough of Staten Island. A knee replacement on his natural leg disqualifies him from actually running; one leg must be intact by the rules of the race.

He lost his limb as a young man when a runaway car crashed into him at a New Jersey gas station.

Traum was a member of New York Road Runners, the club led by Fred Lebow, a Romanian-born New Yorker and avid runner whose energy fueled the early efforts to expand and elevate the marathon to a global level. Even after his death, Lebow symbolizes the race, his statue standing near the Central Park finish line.

For the city”s first five-borough run, Lebow, Hirsch and Percy Sutton, Manhattan”s borough president, had persuaded Mayor Abe Beame to ban traffic from the route that spanned the whole city. On the sidelines were tens of thousands of spectators  a far cry from the 2 million or so now cheering on runners.

The three men told the mayor that the crime-ridden, nearly bankrupt New York of the mid-1970s “needed the marathon to lift the city”s spirits,” Hirsch says.

Rodgers and Shorter”s payments were legal but defied a regulation of the sport”s governing body, now called USA Track & Field, which classified marathoners as unpaid amateurs. Many struggled financially.

New York spurred the worldwide running boom, with ordinary people huffing and puffing their way through big urban marathons that followed in London, Amsterdam, Paris, Tokyo, Shanghai and elsewhere.

The Boston Marathon is the oldest, launched in 1897.

On the first Sunday in November, when exhausted participants finally finish, some collapsing into the arms of loved ones, many take away new friendships while collecting funds for more than 300 charities.

Four decades after a small group of hard-core enthusiasts started it, the NYC Marathon has become an athletic and social democracy.

“In every neighborhood, spectators come at us with a lot of enthusiasm  and that may be conga drums, it may be somebody banging on cookware,” says Paul Fetscher, who ran in 1976. “You get to see the best neighborhoods, you get to see the worst, you get to see the richest, you get to see the poorest, and you get to see the immigrant population of Brooklyn, where more than a million people were not born in the United States.

“But they all love sport,” he adds. “And running is the most basic of all sports: left foot, right foot, left foot, right foot.”

In 1976, Fetscher aced the race in 2:29.

At 70, still working in commercial real estate, he plans to run the 26.2 miles again.